Hi,
The Canon TR7020 is listed in About AirPrint - Apple Support as a model supporting the AirPrint technology. Additional drivers should not be needed when the printer and the computer are connected to the same network (Wi-Fi router).
In case of difficulties with AirPrint, and if the setup is OK, one could try the following procedure:
Power off the Wi-Fi router, the printer, the Mac, and all other devices/computers. Wait two to three minutes. Power on the router. Wait two to three minutes. Power on the printer. Wait a minute or two. Power on the Mac. Finally, power on all other devices/computers.
Add a printer on Mac – Apple Support (UK)
Reset the Mac printing system to solve a problem – Apple Support (UK)
If necessary, you could also use an iPhone or iPad to test AirPrint via the Wi-Fi network.
Use AirPrint to print from your iPhone, iPad, or iPod touch - Apple Support